<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* 选中有 placeholder 属性的元素 */
    [placeholder] {
      border: 1px solid red;
    }

    /* 选中 type 属性值为 password 的元素 */
    [type="password"] {
      border: 1px solid orange;
    }
  </style>
</head>

<body>
  <input type="text" placeholder="请输入">
  <input type="password">
</body>

</html>